Slide rule



8- 13, 1946- A. L. SNEDAKER 2,405,720

SLIDE RULE 'Filed Aug. 22, 1945 2 Sheets-Sheet 1 lNvENToR:

Jib L; a;

ATTORNEY.

Patented Aug. 13, 1946 UNITED STATES PATENT OFFICE SLIDE RULE Albert L.Snedaker, Haddon Heights, N. J. Application August 22 1945, Serial No.611,963

7 Claims. 1

My invention relates to improvements in slide rules, and moreparticularly to built-in magnify ing means therefor to enable a user toread more facilely the graduations marked on the slide rule.

The more commonly used sizes of slide rules are the small pocket sizewhich is approximately six inches in length, and the standard size whichis approximately twelve inches in length. Some of the graduations onslide rules of such lengths are necessarily fine and it is diihcult attimes to read them. To use an ordinary separate magnifying glass to readsuch fine graduations is very unsatisfactory because a magnifying glassis not always at hand when wanted, is awkward to use, and is alsoinconvenient to carry around.

It has long been desired to overcome such difiiculties, and many meanshave been tried. For example, some forms of prior art slide rules havebeen provided with separate magnifiers consisting of a magnifying lensmounted in a raised frame which is adapted to b detachably secured tothe runner of the slide rule. Other forms have a magnifying lens mountedon supportin legs which are pivotally mounted at their lower ends on therunner, so that the lens may be raised for use, or swung out of wayagainst the face of the slide rule when not in use.

Such forms of magnifying means have been found to be more Or lessobjectionabl because it is necessary that the lens be positioned at someheighth above the face of the slide rule to assure that the magnifyingpower of the lens be sufficient to read the graduation markings clearly.Slide rules of the prior art have been made with the body of the ruleand the slide formed as a plane surface and the prior art magnifyinglens must be positioned about an inch above such plane surface to assurea sufficient magnification of the graduation markings on the slide rule.

One object of my invention is to provide a slide rule with compactmagnifying means which are built into and form part of the runner.

Another object of my invention is to provide a slide rule in which thebody, or fixed member, of the slide rule is formed as a concavely curvedsurface.

Another object-of my invention is to provide a magnifying lens which hasa lower convexly curved surface conforming substantially to the concavecurvature of the body portion of the slide I rule.

Another object of my invention is to provide a magnifying means formedas a compound lens having an upper cylindrical convex surface formed onan axis substantially at right angles 2 to the axis of the lowercylindrical convex surface.

My invention includes the various novel features of construction andarrangement hereinafter more definitely specified.

In said drawings,

Fig. 1 is a side elevation of a single face slide rule embodying myinvention.

Fig. 2 is a plan view of the structure shown in Fig. 1.

Fig. 3 is a vertical sectional view of the structure shown in Figs. 1and 2, and taken on the line 33 in Fig. 2.

Fig. 4 is a side elevation of the magnifying lens indicated in Figs. 1,2 and 3. L

Fig. 5 is an inverted plan view of the lens structure shown in Fig. 2.

Fig. 6 is a side elevation of my invention as embodied in a double-facedrule.

Fig. 7 is a plan view of the structure shown in Fig. 6.

Fig. 8 is an end elevation of the structure shown in Fig. 7.

Fig. 9 is a vertical sectional view taken on the lines 9-9 in Fig. 7.

Referring to the form of my invention shown in Figs. 1 to 5 inclusive;the slide rule includes a body portion, or fixed member, formed of twosections I and 2, each longitudinally grooved, as indicated at 3, toreceive the corresponding longitudinal flanges 4 of the slide 5. Thesections l and 2 are maintained in spaced relationship by end members 6and 1. Each of the members 6 and l is conveniently fixed in integralrelationship with said section 2. The respective opposit nds of said endmembers 6 and l ar provided with an elongated opening 9 through whichrespective screws l 0 extend into screw threaded engagement in the screwthreaded openings ll formed at the opposite ends of said section I.

As best shown in Fig. 3, the upper surfaces of the sections 1 and 2 andslide 5 are formed as a concave surface. Although one surface of theslide 5 is shown in Fig. 3 as a concave surface, the slide 5 may beformed with plane surfaces without affecting the functioning of myimproved magnifying means as hereinafter described. Each of the sectionsl and 2 and slide 5 is provided with a series of longitudinalgraduations in the usual manner, as indicated at l2, although only asmall portion of such graduations is shown for c0nvenience and to avoidconfusion in th drawings.

The runner, generally indicated at I3, is comprised of the oppositelycounterpart members I5 and I6 respectively embracing the sections l and2. Each of said members l and It is provided with the usual slidingtongue portion ill for sliding engagement in the longitudinal grooves l8formed in said sections l and 2. The member I5 is provided with spacedrecesses H] in which are engaged the respective opposite loose ends ofthe spring 2!]. Said spring 2i] frictionally engages the outer edge ofthe member I, as best indicated in Fig. 2, to maintain said runner l3 inproper sliding relationship with the sections I and 2.

The magnifying lens, generally indicated at 2 I, forms part of therunner and said lens is provided with the oppositely extending flangeportions 23 and 2 3. The flange 23 is provided with the opening 25through which the screw 26 extends into screw threaded engagement withthe matching screw threaded opening 27 formed in said member l5. Theflange member 2 5 is provided with the opening 28 through which thescrew 29 extends into screw threaded engagement with the matching screwthreaded opening 38 formed in the member H5. The lens 2i may be formedfrom glass, plastic, lucite, or any of the well known transparentmaterials.

The magnifying lens 25 is formed conveniently as a compound lensincluding an upper cylindrical convex surface portion, 32 formedon anaxis substantially at right angles to the axis of the lower cylindricalconvex surface portion 3%. As best shown in Fig. 3, the lowercylindrical convex surface 34 is formed with a curvature substantiallythe same as the curvature of the concave surface of the slide rule, butthe lens 2! is so mounted that the surface 36 is maintained out ofcontact and in spaced relation with the concave surface of the rule.

As best shown in Figs. 2 and 5, the surface Ji l is provided with thefine hairline to indicate precisely in the usual manner the fractionalgraduation desired.

In Figs. 6 to 9, inclusive, I have shown my invention incorporated in adoubl faced slide rule. Referring to Figs. 6 to 9, the slide ruleincludes a body portion, or fixed member, formed of two sections 41 and42, each longitudinally grooved, as indicated at 43, to receive thecorresponding longitudinal flanges Ml of the slide 5. The sections 4!and 52 are maintained in spaced relationship by the bifurcated endmembers 46 and 41, of the section 32, which engage within theirbifurcated arms the opposite ends of the section 4|. Each of the members55 and ll is conveniently formed in integral relationship with saidsection 42. The upper portions of said bifurcated end members and 117are provided respectively with elongated openings to through whichrespective screws 50 extend through matching openings in the section dlinto screw threaded engagement in the matching openings formed in theunderlying arm.

As best shown in Fig. 9, the opposite outer graduated surfaces of thesections ll and t2 and slide 45 are formed as concave surfaces. Althoughthe surfaces of the slide d5 are shown in Fig.9 as concave surfaces, theslide may be .formed with plane surfaces without affecting thefunctioning of my improved magnifying means as hereinafter described.

Each of the sections 4! and i2 and slide 45 is provided with a series oflongitudinal graduations in the usual manner, as indicated at 52,although only a small portion of such graduations is shown forconvenience.

The runner, generally indicated at 53, is comprised of the oppositemembers 55 and 5% respectively embracing the sections ll and 42.Although said members 55 and 56 are shown in sliding engagement with anungrooved edge surface of the members ll and 42, it is obvious that saidmembers 55 and 56 may be provided with a sliding tongue portion forsliding engagement in a groove formed in the sections M and 42 in thesame manner as heretofore described with reference to the form of myinvention shown in Figs. 1 to 5 inclusive.

The member 55 is provided with spaced recesses 59 in which are engagedthe respective opposite loose ends of the spring 6!]. Said spring fillfrictionally engages the edge surface of the member 4|, as bestindicated in Fig. '7, to maintain said runner 53 in proper slidingrelationship with the sections Ill and 42.

The magnifying lenses, generally indicated at El and 6!, form part ofthe runner and are identical in construction but assembled in oppositelycounterpart position. Each of the lenses iii and 6! is provided withoppositely extending flange portions 63 and 6 5. The flanges 83 areprovided with openings through which screws ts extend into screwthreaded engagement with matching screw threaded openings formed in saidmember 55, and the flanges 56 are provided with openings through whichthe screws 69 extend into screw threaded engagement with the matchingscrew threaded openings formed in the member 56. The lenses 6i and 6 Imay be formed of any of the well known transparent materials, as hasbeen hereinabove stated with reference to the lens 2! of the form of myinvention shown in Figs. 1 to 5 inclusive.

The lenses 6! and 6f being identical, only the lens Bl will bedescribed. Said lens BI is formed as a compound lens including an uppercylindrical convex surface portion 52 formed on an axis substantially atright angles to the axis of the lower cylindrical convex surface portion74. As best shown in Fig. 9, the lower cylindrical convex surface M isformed with substantially the same curvature as the curvature of theconcave surface of the slide rule, but the lens BI is so mounted thatthe surface "M is maintained out of contact and in spaced relation withthe concave surface of the rule. As best indicated in Fig. '7 withreference to the lens 6!, the respective surfaces 14 of the lenses 6iand 5! are provided with the fine hairline 15 to indicate precisely thefractional graduation desired.

It is obvious that various modifications may .be made in my inventionwithout departing from the essential features thereof as defined in theappended claims and, therefore, I do not desire to limit myself to theprecise details of construction and arrangement hereinbefore set forth.

I claim:

1. A slide rule comprising a body portion having a concavely curvedface; and a convexly curved lens slidably mounted on said body portionwith the convexly curved surface of said lens in substantiallyconcentric close juxtaposition to said concavely curved face.

2. A slide rule comprising a body portion having a concavely curvedface; a slide member having a concavely curved. face; and a convexlycurved lens slidably mounted on said body portion with the convexlycurved surface of said lens in substantially concentric closejuxtaposition to said concavely curved faces of said body portion andsaid slide. 1

3. A slide rule comprising a body portion having a concavely curvedface, and a convexly curved cylindrical section lens sliclably mountedon said body portion with the convexly curved surface of said lens insubstantially concentric close juxtaposition to said concavely curvedface.

4. A slide rule comprising a body portion having a concavely curvedface; a slide member having a concavely curved face; and a convexlycurved cylindrical section lens slidably mounted on said body portionwith the convexly curved surface of said lens in substantiallyconcentric close juxtaposition to said concavely curved faces of saidbody portion and said slide.

5. A slide rule as in claim 1; wherein said lens is formed as a compoundlens having an upper convexly curved cylindrical section portion formedon an axis which is substantially at right angles to the axis of saidfirst mentioned convexly curved surface.

6. A slide rule as in claim 2 wherein said lens is formed as a compoundlens having an upper convexly curved cylindrical section portion formedon an axis which is substantially at right angles to the axis of saidfirst mentioned con- Vexly curved surface.

'7. A slide rule as in claim 3; wherein said lens is formed as acompound lens having an upper convexly curved. cylindrical sectionportion formed on an axis which is substantially at right angles to theaxis of said first mentioned convexly curved cylindrical sectionportion.

ALBERT L. SNEDAKER.

